A goal of the cochlear physiology laboratory is to understand how the components of the organ of Corti enhance the sound induced vibration of the basilar membrane, a process known as cochlear amplification (CA). Two questions of broad interest are to be studied; how do the outer hair cells transmit force to activate the CA and what is the mechanical role of the tectorial membrane in CA? Standard techniques are clearly insufficient for answering these questions, so new and innovative methodology will be used. The Fourier Domain Optical (Low) Coherence Tomography (FDOCT) system that we developed gives unique possibilities for studying CA. Using this method; we propose to determine how the complex motion of the organ of the Corti, powered by OHC forces, results in mechanical stimulation of the inner hair cell stereocilia. This is the critical first step in hearing, the stiulation of inner hair cells. We also propose to determine whether the tectorial membrane has a mechanical resonance relevant to organ of Corti function. This is fundamental to understanding how the displacement of the stereocilia hair bundles on outer hair cells can have the proper timing to make effective any force that they actively produce. The distribution of outer hair cell activity is fundamental to knowing how the traveling wave propagates. The spatial distribution of the CA is studied with FDOCT and mathematical modeling.